Red oxide & fire board on RSJs

[pls1]

In what situations is red oxide primer and/or fire rated plasterboard required on RSJs or Universal Beams?
If the beam was totally internal and not somewhere exposed then I can see why red oxide might not be required but what about fire board ? Is this now required on all new beam installations (or double up 12.5mm plasterboard)

 

[RonnyRaygun]

Red Oxide is a primer and does not protect from exposure to moisture, whether the beam is internal or external.
To protect a beam from corrosion it will need a corrosion resistant paint spec or galvanising.

As for fireboard, you just have to ensure that the beam is protected from fire for the length of time that the regs state. Plasterboard will do this if thick enough.

 

[Cabbyfan]

Just put in a 2.5m steel beam in my kitchen and BC insisted on fireboard or 2 layers of plasterboard.

 

[ban-all-sheds]

OOI, how would the rest of the house structure be faring at the point when a fire would have caused an unprotected RSJ to fail?

 

[tony1851]

OOI, how would the rest of the house structure be faring at the point when a fire would have caused an unprotected RSJ to fail?

Steel rapidly looses strength above (IIRC) around 500 deg. House fires can quickly reach and exceed that temperature.
Other main supporting elements, such as walls and - yes -timber floors, can survive much longer, but that's no use if the beam supporting them fails.

 

[jeds]

Agreed. Steel beams are often the first thing to go in a fire. Older roof beams in open plan factories have been the cause of many fire-fighter deaths over the years.

 

[mikeey84]

I remember seeing a documentary stating that if the central columns of the WTC were made out of oak they would have fared better than they did in the fire.